Effects of proximity to riparian zones on avian species richness and abundance in montane aspen woodlands

Abstract

ABSTRACT. Riparian zones often provide more food or nesting resources than surrounding ecosystems and thus support more species or a greater abundance of birds. However, the extent to which the positive effects of riparian zones extend into adjoining habitats has rarely been investigated. We examined bird species richness and abundance in aspen (Populus tremuloides) woodlands of the upper East River Valley in Colorado, a region with extensive stands of aspen located upslope from riparian zones dominated by willows (Salix spp.). Our objective was to determine how species richness and abundance in aspen stands located closer to riparian zones compared to that of aspen stands farther away. To control for elevation effects, we conducted point counts for birds and examined the effects of riparian proximity on avian species richness and abundance in three elevation belts (low, 2840-2875 m; middle, 2940-2960 m; and high, 3040-3060 m). We determined riparian proximity by measuring distances from each census site to the nearest body of water and to the nearest patch of willow. Proximity to major willow patches (ࣙ6500 m 2 ) had a stronger influence on species richness and abundance than did proximity to water or smaller patches of willows. Total species richness and abundance significantly increased with proximity to major willow patches at low elevation sites only. This relationship was driven by a greater prevalence of riparian-nesting species at lower elevation sites, where aspens were generally closer to riparian zones. The positive effects of willows diminished with abrupt changes in elevation. Our results highlight the importance of protecting willows around riparian zones in valley bottoms where habitat destruction caused by human land use is most prominent. RESUMEN. Efectos de la proximidad a la zona riparia sobre la riqueza y abundancia de especies de aves en bosques montanos deálamo En muchos casos las zonas riparias proveen una mayor cantidad de alimentos o recursos para la anidación que los ecosistemas circundantes. Por lo tanto tienen un mayor numero de especies o una mayor abundancia de aves. Sin embargo, la medida en que los efectos positivos de las zonas riparias se extiende hacia hábitats adjuntos ha sido raramente explorada. Examinamos la riqueza de aves y la abundancia en bosques deálamo (Populus tremuloides) en la parte alta del "East River Valley" en Colorado, una región con poblaciones extensas deálamo ubicadas en cerca de zonas riparias dominadas por sauces (Salix spp.). Nuestro objetivo era determinar el cambio en la riqueza y abundancia de especies de aves en los bosques deálamo de acuerdo con la distancia a la zona riparia. Para contralar por los efectos de la elevación, realizamos puntos de conteo para aves y examinamos los efectos de la proximidad a zonas riparias sobre la riqueza y abundancia de aves en tres franjas altitudinales (baja, 2840-2875 m, medio 2940-2960 m y alto, 3040-3060 m). Tomamos la distancia desde cada punto de censo hasta el cuerpo de agua mas cercano como la proximidad a la...

Does Type, Quantity, and Location of Habitat Matter for Fish Diversity in a Great Plains Riverscape?

“…Third, the spatial arrangement of habitats (e.g., placement of habitats and the identity of neighbors) matters. While characteristics of neighboring habitats have been shown to influence species diversity in terrestrial ecosystems (Glass and Floyd 2015), examinations in aquatic ecosystems is limited. Our finding that neighbor habitats can alter characteristics of target habitats in aquatic ecosystems is novel and can explain natural variability that is especially common in lotic field studies.…”

Fisheries Volume 46 Number 10 October 2021

“…Third, the spatial arrangement of habitats (e.g., placement of habitats and the identity of neighbors) matters. While characteristics of neighboring habitats have been shown to infl uence species diversity in terrestrial ecosystems (Glass and Floyd 2015 ), examinations in aquatic ecosystems is limited. Our fi nding that neighbor habitats can alter characteristics of target habitats in aquatic ecosystems is novel and can explain natural variability that is especially common in lotic fi eld studies.…”